In a power supply diagram, which block indicates a pulsating dc output?
-
transformer -
filter -
rectifier -
regulator
Since diodes are destroyed by excessive current, circuits must have:
-
higher voltage sources -
current limiting resistors -
more dopants -
higher current sources
Providing a constant output regardless of ac input or load resistance changes is the function of a:
-
transformer -
filter -
regulator -
rectifier
When a diode is forward biased, the voltage across it
-
is directly proportional to the current -
is inversely proportional to the current -
is directly proportional to the source voltage -
remains approximately the same
Which of the following circuits would require the least amount of filtering?
-
A half-wave rectifier -
A full-wave rectifier -
A bridge rectifier -
A full-wave rectifier and a bridge rectifier
With a 12 V supply, a silicon diode, and a 370-ohm resistor in series, what voltage will be dropped across the diode?
-
0.3 V -
0.7 V -
0.9 V -
1.4 V
Shunting the ac component away from the load is the task of a:
-
transformer -
filter -
regulator -
rectifier
List three diode packages:
-
clip package, DIP, small current package -
DIP, small current package, large current package -
small current package, large current package, and SIP -
small current package, large current package, clip package
A diode for which you can change the reverse bias, and thus vary the capacitance is called a
-
varactor diode -
tunnel diode -
zener diode -
switching diode
A filtered full-wave rectifier voltage has a smaller ripple than does a half-wave rectifier voltage for the same load resistance and capacitor values because:
-
there is a shorter time between peaks -
there is a longer time between peaks -
the larger the ripple, the better the filtering action -
none of the above
When a diode is destroyed it has infinite impedance. When damaged by heat it will probably:
-
short -
conduct more -
conduct less -
open
The characteristic curve for the complex model of a silicon diode shows that
-
the barrier potential is 0 V -
the barrier potential stays fixed at 0.7 V -
the barrier potential increases slightly with an increase in current -
the barrier potential decreases slightly with an increase in current
Why is heat produced in a diode?
-
due to current passing through the diode -
due to voltage across the diode -
due to the power rating of the diode -
due to the PN junction of the diode
The arrow in the schematic symbol of a diode points to
-
the n-type material, which is called the anode -
the n-type material, which is called the cathode -
the p-type material, which is called the anode -
the p-type material, which is called the cathode
What is a varistor?
-
a voltage-dependent resistor -
a voltage-dependent diode -
a current-dependent resistor -
a current-dependent diode
An LED can be tested with an ohmmeter.
-
True -
False
A rectifying diode can change ac voltage to dc voltage.
-
True -
False
Atoms in a silicon crystal are held together by ___ bonds.
-
crystal -
chemical -
electrical -
covalent
If the frequency of the applied ac signal to a half-wave rectifier is 60 Hz, the frequency of the pulsating dc output will be
-
30 pps -
60 pps -
90 pps -
120 pps
A pn junction allows current flow when
-
the p-type material is more positive than the n-type material -
the n-type material is more positive than the p-type material -
both the n-type and p-type materials have the same potential -
there is no potential on the n-type or p-type materials